diff --git a/aoc2015/src/day02.rs b/aoc2015/src/day02.rs
index 79aa3ec..874a109 100644
--- a/aoc2015/src/day02.rs
+++ b/aoc2015/src/day02.rs
@@ -29,7 +29,7 @@ fn wrapping_paper(present: &Present) -> u64 {
 }
 
 fn part1(presents: &[Present]) -> u64 {
-    presents.iter().map(|p| wrapping_paper(p)).sum()
+    presents.iter().map(wrapping_paper).sum()
 }
 
 fn ribbon_bow_length(present: &Present) -> u64 {
@@ -49,7 +49,7 @@ fn ribbon_needed(present: &Present) -> u64 {
 }
 
 fn part2(presents: &[Present]) -> u64 {
-    presents.iter().map(|p| ribbon_needed(p)).sum()
+    presents.iter().map(ribbon_needed).sum()
 }
 
 struct Present {
diff --git a/aoc2019/src/day08.rs b/aoc2019/src/day08.rs
index 1d6d6d2..8c493d3 100644
--- a/aoc2019/src/day08.rs
+++ b/aoc2019/src/day08.rs
@@ -84,12 +84,12 @@ impl FromStr for Image {
 
         let lines = digits
             .chunks(IMG_WIDTH)
-            .map(|chunk| chunk.to_vec())
+            .map(<[_]>::to_vec)
             .collect::<Vec<Vec<u8>>>();
 
         let layers = lines
             .chunks(IMG_HEIGHT)
-            .map(|chunk| chunk.to_vec())
+            .map(<[_]>::to_vec)
             .map(|pixels| Layer { pixels })
             .collect::<Vec<Layer>>();
 
diff --git a/aoc2020/src/day20.rs b/aoc2020/src/day20.rs
index 39fbf5f..5961c59 100644
--- a/aoc2020/src/day20.rs
+++ b/aoc2020/src/day20.rs
@@ -59,7 +59,7 @@ enum Rotation {
 ///
 /// Note: we don't need a horizontal and a vertical flip, these result in the same output as a 180
 /// degree rotation when combined, so only one is necessary
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Default, Clone, Copy)]
 struct Transform {
     flip: bool,
     rotation: Option<Rotation>,
@@ -121,15 +121,6 @@ impl Transform {
     }
 }
 
-impl Default for Transform {
-    fn default() -> Self {
-        Self {
-            flip: false,
-            rotation: None,
-        }
-    }
-}
-
 #[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
 enum Position {
     Down,
diff --git a/aoc2020/src/day24.rs b/aoc2020/src/day24.rs
index 9992e86..ab6cb28 100644
--- a/aoc2020/src/day24.rs
+++ b/aoc2020/src/day24.rs
@@ -133,7 +133,7 @@ fn part2(input: &str) -> Result<usize> {
 /// These use the axial coordinates described here:
 ///
 /// https://www.redblobgames.com/grids/hexagons/#coordinates-axial
-#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
+#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq)]
 struct HexCoordinates {
     q: i64,
     r: i64,
@@ -188,12 +188,6 @@ impl HexCoordinates {
     }
 }
 
-impl Default for HexCoordinates {
-    fn default() -> Self {
-        Self { q: 0, r: 0 }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;